Through prolonged personal experience, especially with an illness or a recurring problem, one becomes knowledgeable or an expert in that particular area.
他虽然不是专业的园艺师，但自家花园打理了几十年，久病成医，对各种植物的习性了如指掌。
Although he is not a professional gardener, he has been tending his own garden for decades. Through this long experience, he has become an expert, knowing the habits of various plants inside out.
Era:
Ancient
Frequency:
Next Idiom